The device for producing ethoxylation derivatives at the prior comprises a reactor with a vacuumizing pipe, an evacuation pipe, a nitrogen input pipe, a chain initial dose feed inlet, an ethylene oxide feed inlet and circulation loop. A certain amount of chain initial dose is needed to start the circulation pump of the circulation loop of ethoxylation reaction, if the amount of the chain initial dose is little, the starting quantity of the circulation pump is low, and then only small circulation pump, small size of connecting pipe and the heat exchanger with low thermal load are needed, and the adding flow rate of ethylene oxide is relatively low, although this kind of setting is provided with very high growth rate, the reaction time is long and the output of the device is low. If the adding flow rate of ethylene oxide is enhanced, big circulation pump, big size of connecting pipe and the heat exchanger with high thermal load are needed, meaning large amount of chain initial dose, this kind of setting is provided with short reaction time, high output, increased cost of chain initial dose and low growth rate.